this post was submitted on 08 Feb 2024

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What's the dumbest thing you thought as an adult that you recently learned was wrong? (self.asklemmy)

submitted 9 months ago* (last edited 9 months ago) by cheese_greater to c/asklemmy

189 comments fedilink hide all child comments

I just realized while cooking that a measuring-cup cup (as measured out as 250mL in a glass measuring cup) is the same amount(s) as one of the actual plastic baking measuring cups that go inside each other like Russian dolls lol

I thought they were different somehow (something something imperial metric yadda yadda yaddda)

Your turn to come clean Lemmings!

**EDIT: to clarify, I mean volumetrically for measuring liquids

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[–] pandacoder 5 points 9 months ago (2 children)

The reflection is only bidirectional if you can see the other person's eyes.

It's like if someone is in a bathroom stall. You could see the stall is occupied by seeing their feet stick below the wall of the stall, but they cannot necessarily see any part of you since their eyes are not where their feet are.

Same principle applies to reflections, where maybe the body part that you can see is just the top of the head, and since the person isn't tall enough they can't see that you can see them.

[–] [email protected] 1 points 9 months ago

If you can see their eyes, they can see your eyes. But it's possible you can see some of them without them being able to see you, or the other way around. Unless your eyes are the only part of you (because you're a camera), you need more information in order to know they can't see you.

[+] rdyoung -7 points 9 months ago (1 children)

Even when you can see their eyes that isn't always the case. It depends on how sharp the angle is and where you and they are relatively speaking. You can definitely see their eyes without them seeing you.

[–] [email protected] 4 points 9 months ago (1 children)

Definitely not.

[–] rdyoung -3 points 9 months ago* (last edited 9 months ago) (2 children)

Definitely yes. I'm amazed (but not surprised) by the lack of understanding of this concept.

I suggest that everyone here play around with mirrors and learn something themselves.

I'll leave you with this. Why do mirrors work to see around corners when you are trying to not be seen?

This might help explain things.

https://www.iflscience.com/how-can-a-mirror-see-an-object-that-is-hidden-by-a-piece-of-paper-68363#:~:text=As%20long%20as%20there%20is,employ%20some%20pretty%20hardcore%20science.

[–] [email protected] 3 points 9 months ago

That link shows that Mario would see your eyes in the mirror. Those light rays work in both directions. If you can see Mario's eyes, Mario's eyes can see yours. This is clearly shown in that link.

People use mirrors to covertly look around corners because the mirrors they use are smaller than their head. And if the mirror is still spotted getting a bullet in the mirror is much less lethal than getting a bullet in the head. It has nothing to do with the mirror somehow being magically invisible to whoever is around the corner.

[–] wolfpack86 1 points 9 months ago (1 children)

You are wildly misunderstanding the effect at play. All this says is peoples brains are inherently misinterpreting the angles

[+] rdyoung -3 points 9 months ago (1 children)

[removed by mod]

[–] pandacoder 2 points 9 months ago (1 children)

You can see other people in a reflection without them being able to see you.

It is not possible to see someone else's eyes (except from the side, so it's only seeing their eyes in profile) in a reflection without them being able to see you too.

It's literally not possible via reflection, as everything is equal and opposite. If light can go from their eyes to yours, it's also possible to go the opposite direction.

This is what everyone has been saying but instead of thinking through everything clearly, you resorted to bullying.

The only way to accomplish this one-way vision is by adding something that is not reflection to the system (like a one-way window), but that's breaking the premise under which everyone else has been commenting in good faith.